Electrical switch having contact grounded by external tab on casing



April 25, 1967 JQ M.

ELECTRICAL SWITCH HA COBB 3,316,365 VING CONTACT GROUNDED BY EXTERNAL TAB ON CASING Filed Feb. 2s, 196e l N VENTOR Jesse LM. Cobb zZ/M M @wg/77M @figg United States Patent O 3,316,365 ELECTRICAL SWITCH HAVING CONTACT GROUNDED BY EXTERNAL TAB N CAS- ING Jesse M. Cobb, Glenview, Ill., assignor to Indak Manufacturing Corp., Northbrook, Ill., a corporation of Illinois Filed Feb. 28, 1966, Ser. No. 530,453 10 Claims. (Cl. 200-16) This invention relates particularly to electrical switches intended for automotive and similar uses, but is applicable to electrical switches generally.

One object of the present invention is to provide an electrical switch in which at least one contact of the switch is grounded to the casing of the switch in a new and improved manner.

A further object is to provide such a new and improved switch in which the contact is grounded by means of an external tab or similar element formed integrally on the casing, the grounded contact being riveted or otherwise secured to the tab.

It is a further object to provide such a new and improved switch in which the tab or similar element provides a ground connection which is secure and reliable, and which affords an extremely low resistance to ground, yet at extremely low cost, whereby the cost and electrical resistance of -a separate grounding lead are avoided.

Further objects and advantages of the present invention will appear from the following description, taken with the accompanying drawings, in which:

FIG. l is a fragmentary side elevational view of an electrical switch to be described as an illustrative embodiment of the present invention.

FIG. 2 is a fragmentary rear view of the switch.

FIG. 3 is a fragmentary enlarged cross section taken generally along the line 3 3 in FIG. 2.

FIG. 4 is a fragmentary cross section showing the switch in a partially assembled condition, at an early stage in the manufacture of the switch.

FIG. 5 is a fragmentary side elevational view of a modified switch.

FIG. 6 is an elevational view of the modified switch in a partially assembled condition, corresponding to the stage of assembly shown in FIG. 4.

It will be seen that FIG. l illustrates an electrical switch 1l) which is especially well adapted for automotive service, for use on automobiles, trucks or the like, but will also find many other applications. The illustrated switch 10 comprises an electrically conductive casing 12 which preferably is made of metal. -As shown, the casing 12 is formed from sheet metal into a rectangular shape, -but the present invention is applicable to casings of various shapes and constructions.

A contactor 14 is movably mounted within the casing 12, preferably on a movable carriage 16. As shown, the carriage 16 is slidable longitudinally along the inside of the casing 12. The illustrated casing 12 has a front wall 18 and a pair of longitudinal side walls 20 and 22 which serve as guides for the carriage 16. The casing 12 has a pair of end walls 24 and 26 which retainl the carriage within the casing.

Various means may be provided for operating the carriage 16. In the illustrated construction, for example, the switch is provided with an operating lever 28 which is swingable about a pivot 30, mounted on a bracket 32 projecting forwardly from the casing 12. The lever 28 has an arm 34 which projects rearwardly into the casing 12 and is received in an opening 36 formed in the carriage 16. A slot or opening 38 is formed in the front wall 18 of the casing to receive the arm 34.

3,316,365 Patented Apr. 25, 1967 ice The contactor 14 is movable into engagement with a plurality of contacts or points. F our such contact points 41-44 are provided in the illustrated construction. At least one of the contact points is grounded directly to the casing 12. In the illustrated construction the contact 41 is thus grounded, in a manner to ybe described in detail presently.

The contacts 41-44 are mounted on a supporting member 46 made of insulating material. The member 46 preferably takes the form of Ian insulating board or plate which is secured to the casing 12 so as to form the rear wall thereof.

A plurality of tabs 48 or other fastening elements are formed on the casing 12 to retain the insulating plate 46. The illustrated tabs 48 extend through slots or notches 50 which are formed in the edge portions of the insulating plate 46. The tabs 48 are bent or clinched inwardly, behind the insulating plate 46, so that the plate will be securely fastened to the casing.

The contacts 41-44 preferably take the form of rivets which extend through suitable openings 51 in the insulating plate 46. Terminals 52-54 of suitable construction are preferably secured to the rear ends of the ungrounded rivets 42-44 and against the rear or outer side of the insulating plate 46.

Suitable spring means are provided to press the contactor 14 rearwardly against the contacts 41-44 and also against the insulating plate 46. Thus, one or more springs may be provided between the contactor 14 and the carriage 16. In the illustrated construction a coil spring 56 is compressed between the contactor 14 and the carriage 16.

The illustrated contactor 14 is retained and guided on the carriage 16 by means of guide tabs or lugs 58y which project from the contactor toward the vfront of the switch. The tabs 56 are slidably retained in notches or slots 60 which are formed in the carriage 16.

In addition to Ibiasing the contactor 14 rearwardly against the contacts 41-44, the spring 56 biases the carriage 16 against the front wall 18 of the casing 12. It is preferred to provide detent elements on the front wall 18 and also on the carriage 16 to locate and detain the carriage in its various operating positions. The detent elements on the illustrated carriage take the form of ridges or lugs 62 which project forwardly therefrom. As to the front wall 18, the detent elements take the form of altern-ate ridges 64 and grooves 66, adapted to receive the ridges 62. When the carriage 16 is moved along the inside of the casing, the detent projections 62 ride over the ridges 64 and into the grooves 66. Due to the biasing action of the spring 56 the detent projections 62 are detained in the grooves 64.

As already indicated, the grounded contact 41 is connected directly to the casing 12. When mounted in an automobile or the like, the casing is normally connected to the body of the automobile. Thus, the casing becomes part of the grounded side of the electrical system.

To provide for the grounding of the contact 41, the casing 12 is provided with an external member 68- which is formed integrally with the casing `and is riveted or otherwise secured to lthe grounded contact. The illustrated member 6 '8 takes the form of a tab or flange which projects rearwardly from one wall `20 of the casing. The illustrated tab 68 is generally L-shaped and is formed with first and second legs 70 and 72 at right-angles to each other. The first leg 70 extends rearwardly from the casing through a slot or notch 74 which is formed in the insulating plate 46. The second leg 72 is mounted against the rear side of the insulating plate 46. The contact rivet 41 extends through an opening 76 in the second leg 72 and is securely clinched or upset against the leg 72. In

this way, .a secure electrical and mechanical connection is formed between the contact rivet 41 and the grounding tab or fiange 68.

In the manufacture of the switch, the casing 12 is preferably formed initially with the grounding tab 68 bent outwardly at an angle to its final position. The .grounding tab 68 is shown in such an initial position in FIG. 4. With the grounding tab 68 in this position, it is an easy matter to insert the contact rivet 41 through the insulating plate 46 and the tab 68. The rivet 41 may then be upset or clinched so that the insulating plate 46 will be securely clamped against the rear leg 7.2 of the tab 68.

The assembly of the switch is completed by mounting the carriage 16, the spring S6 and the contactor 14 within the casing7 and then swinging the insulating plate 46 into its final position against the rear side of the casing 12, .as indicated by the curved arrows in FIG. 4. In this way, the grounding tab 68 is bent into its final position, as shown in FIG. 3. In order to insure that the bending operation will be carried out easily and accurately, a groove or score mark 78 may be formed in the casing 12 at the junction between the tab 68 and the side wall 20. When the insulating plate 46 is swung into its final position, the tab 68 will bend easily at the score mark 78. The insulating plate 46 is secured in its final position by clinching the tabs 48.

FIGS. and 6 illustrate a modified switch 80 in which the contact 41 is grounded to the casing 12 by means of a grounding tab or liange 82 having a plurality of webs or legs 84 which are connected to the side wall 20 at spaced points. The webs 84 correspond to the leg '70 of FIGS. 3 and 4. However, two or more webs 84 are provided and are spaced apart along the length of the side wall 20. The grounding tab or fiange 82 also has a rear leg 86 which corresponds to the leg 72 of FIGS. 3 and 4. The webs or legs 84 project through slots or notchesl 88 which are formed in the insulating plate 46.

The provision of a plurality of spaced webs 84 makes it easy to bend down the grounding tab 82 in the correct direction and with a high degree of precision, so that the insulating plate 46 Will be accurately located on the rear side of the casing 12. The webs 84 are preferably made quite narrow to facilitate the bending operation. The provision of two or more narrow webs insures that the grounding tab may be bent into its final position without bending the side wall of the casing. The use of two or more connecting webs 84 on the grounding tab provides an extremely secure and rigid connection between the insulating plate 46 and the casing 12. As in the case of the construction of FIGS. 3 and 4, the contact rivet 41 extends through an opening 89 in the rear leg S6 of the grounding tab 82.

As before, the grounding tab 82 is initially bent rearwardly and outwardly at approximately 90 degrees to its final position. In this way, it is easy to insert and set the contact rivet 41 so that the insulating plate 46 will be secured to the grounding tab 82. The insulating plate 46 is then swung against the casing 12 so as to bend the grounding tab 82 to its final position, las shown in FIG. 5.

Various arrangements of the contacts 41-44 may be employed. As shown, the contacts 42 and 43 are in one row, while the contacts 41 and 44 are in a parallel row. The contacts 42 and 43 are staggered relative to the contacts 41 and 44.

When the contactor 14 is in its uppermost position, as illustrated in FIG. 2, the contactor engages only the contact 42. This position constitutes the Off position of the switch. The contactor 14 may be moved downwardly to its first operating position, in which the contactor engages the grounded contact 41, in addition to the contact 42. An insulating point or boss 90 may be provided on the insulating plate 46 to engage the contactor 14 so as to provide three definite points of contact with the contactor. The insulating bossv 90 is preferably in the form of a semi-perforation, extruded or stamped forwardly from the insulating plate 46.

Further downward movement of the contactor 14 brings it to its next operating position, in which the contactor engages the contacts 41, 42 and 43. When the contactor is moved downwardly to its lowermost position, it engages the contacts 41, 43 and 44.

The switch may be employed in a variety of circuits to carry out various control functions. Such a circuit is shown by w-ay of example in FIG. 2. The illustrated circuit is adapted to control the speed of a motor 92 for a blower or other device. The motor 912 is connected between the contact 44 and the ungrounded side of a battery 94. Of course, the other side of the battery is grounded and thus is connected to the contact 41, which is grounded through the casing 12. A resistor 96 is connected between the contacts 43 and 44. Another resistor 98 is connected between the contacts 42 and 43.

When the contactor 14 is in its uppermost position, the motor 92 is off, because the energizing circuit to the grounded contact is open. When the contactor 14 is moved downwardly so as to engage the grounded contact 41, the energizing circuit for the motor 92 is completed through the resistors 96 and 98, so that the motor operas a low speed. In its next position, the contactor engages the contact 43 so as to short-circuit .the resistor 98. Thus, the motor is energized through the resistor 916, so that the motor operates at medium speed.

In the final or lowermost position of the contactor 14, a direct circuit is formed between the grounded contact 41 and the contact 44 so that the motor 92 is energized directly from the battery 94. Thus, the motor operates at maximum or high speed.

It will be Irecognized that the external grounding tabs or flanges provide extremely secure and rigid ground connections between the grounded contact and the casing. Moreover, the ground connection has an extremely low electrical resistance. The external grounding tab, being formed integrally with the casing, provides a ground connection at extremely low cost. The high cost of a separate grounding lead is thus obviated. Moreover, the electrical resistance of such a separate lead is avoided.

Various other modifications, alternative constructions and equivalents may be employed without departing from the true spirit and scope of the invention, as exemplified in the foregoing description and defined in the following nflaims.

I claim:

1. In an electrical switch,

the combination comprising a metal casing,

a carriage movable in said casing,

means for moving said carriage Within said casing,

a contactor mounted on said carriage and movable therewith,

an insulating member mounted on said casing opposite said contactor and forming one wall of said casing, at least a first contact mounted on said insulating member and engageable by said contactor, at least one tab formed integrally with said casing and projecting adjacent said insulating member on the side thereof remote from said casing,

and at least a second contact mounted on the inner side of said insulating member and having a portion extending through said insulating member and secured to said tab for connecting said contactor to ground through said casing.

2. A combination according to claim 1, in which said second contact comprises a rivet extending through said insulating member and said tab and clamping said tab against said insulating member.

3. A combination according to claim 1, in which said insulating member is formed with a slot for receiving said tab.

4. A combination according to claim 1, in which said tab is generally L-shaped and is formed with a rst leg extending between the front and rear sides of said insulating member, and a second leg extending adjacent the rear side of said insulating member and connected to said second contact.

5. A combination according to claim 1, in which said tab is scored at the junction between said tab and said casing to provide for accurate and easy bending of said tab during manufacture of said switch.

6. In an electrical switch,

the combination comprising a casing made of conductive material,

a contactor movable in said casing,

means for moving said contactor within said casing,

said means including an insulating carriage supporting said contactor and retained Within said casing for movement along a predetermined path therein,

an insulating member mounted on said casing opposite said contactor,

at least a first contact mounted on `the inner side of said insulating member and engageable by said contactor,

a conductive member formed integrally with said casing and extending adjacent the outer side of said insu' lating member,

and at least a second contact mounted on the inner side of said insulating member and engageable by said contactor, said second contact having a portion extending through said insulating member and connected directly to said conductive member for grounding said contactor through said casing.

7. A combination according to claim 6, in which said casing is made of metal, and said conductive member comprises a ilange formed integrally with said casing and bent behind said insulating member.

8. A combination according to claim 6, in which said Contact comprises a contact rivet extending through said insulating member and said conductive member and securely clamping said members together.

9. A combination according to claim 6, in which said conductive member comprises a ange extending along the outer side of said insulating member, and a plurality of spaced web portions extending between said casing and said ange.

10. A combination according to claim 1, in which said tab comprisesa flange extending behind said insulating member and connected to said second Contact, and a plurality of spaced web portions extending between said flange and said casing.

References Cited by the Examiner UNITED STATES PATENTS 2,743,423 4/1956 Parks 174-51 X 3,271,536 9/1966 Schink 200-16 ROBERT K. SCHAEFER, Primary Examiner.

I. R. SCOTT, Assistant Examiner. 

1. IN AN ELECTRICAL SWITCH, THE COMBINATION COMPRISING A METAL CASING, A CARRIAGE MOVABLE IN SAID CASING, MEANS FOR MOVING SAID CARRIAGE WITHIN SAID CASING, A CONTACTOR MOUNTED ON SAID CARRIAGE AND MOVABLE THEREWITH, AN INSULATING MEMBER MOUNTED ON SAID CASING OPPOSITE SAID CONTACTOR AND FORMING ONE WALL OF SAID CASING, AT LEAST A FIRST CONTACT MOUNTED ON SAID INSULATING MEMBER AND ENGAGABLE BY SAID CONTACTOR, AT LEAST ONE TAB FORMED INTERGALLY WITH SAID CASING AND PROJECTING ADJACENT SAID INSULATING MEMBER ON THE SIDE THEREOF REMOTE FROM SAID CASING, AND AT LEAST A SECOND CONTACT MOUNTED ON THE INNER SIDE OF SAID INSULATING MEMBER AND HAVING A PORTION EXTENDING THROUGH SAID INSULATING MEMBER AND SECURED TO SAID TAB FOR CONNECTING SAID CONTACTOR TO GROUND THROUGH SAID CASING. 